The proposed research program will advance the understanding of findings that the reward of high effort in one-or-more tasks increases the effort subsequently exerted in other tasks. One set of studies, with rats, will examine implications of the theory that pairing the response-produced sensation of effort with a reinforcer causes that sensation to take on secondary-rewarding properties. A second set of studies, with children and rats, will test the theory's implication that rewarded effort influences generalized divergent thinking in children, as well as simpler forms of behavioral variation in non-verbal animals. It is anticipated that the results will increase the understanding of mechanisms underlying learned effort and will contribute to the conceptual basis for further development of reinforcement techniques to ameliorate the low levels of effort expenditure frequently observed in depressed psychiatric patients, learning-disabled students, and students and employees of normal ability who perform poorly in school or on the job. In addition, the research program will increase our understanding of behavioral variation in uncertain environments and help clarify the conditions under which presentations of rewards increase or decrease children's creativity. The findings will have direct implications for the training of children's creativity in the classroom where widespread disagreements concerning the effects of reward on creativity have produced major disparities in educational practice.